There are other circumstances of a hurtful character, operating in general upon the young gentlemen who fill the offices of clerks, and upon the nurses, in these establishments, which we doubt not co-operate with the other circumstances mentioned, in producing the extraordinary amount of disease sometimes observed among them. But of these which will readily suggest themselves to all, it is unnecessary to say much in this place.

It is in the fever wards principally that contagious atmosphere is apprehended.

The young gentlemen officiating as clerks are generally arrived at the most important part of their course of study. They are in preparation for their examination before the colleges, and are often in consequence in a very feeble state of health—which, if not always marked with actual sickness, is often sufficiently indicated by worn out and emaciated systems, and by complexions of a very sallow or sickly colour. They are thus predisposed to fever. The nurses waiting upon fever patients are subject to more fatigue and more interruptions to their rest, on account of the great attention which those under their care require, than the same class of persons are exposed to, who belong to the surgical wards.

A case of an apparently strong nature is made out in favour of the propagation of disease by atmospheric contagion, when a person labouring under sickness or lately recovered from it, is removed into a house or locality in which the same malady shortly manifests itself. It is often held conclusive; we hold it otherwise.

Such a case is known to take place, and we have observed it in our own practice—but that is not entitled to be considered conclusive. It should be shewn, if that inference is at all to be arrived at, that the occurrence is so frequent that the probability is precluded of attributing the phenomena observed to the ordinary causes of disease, that the number who thus suffer is greatly more in proportion than holds among the population generally, and that, in short, those thus visited by the sick are affected in a greater ratio than holds with the general community, as ascertained by an observation of the whole course of the disease or epidemic.

We know that the appearance of disease among those visited by the sick, or those lately recovered, does not always happen. We ourselves, scarcely recovered of typhus fever, have visited and lived with a family at a distance, and no such thing as propagation has occurred—and hundreds of other cases are within our knowledge. We have, after making calculations on the subject, considering both those cases, where disease did occur and where it did not, that, generally speaking, those visited by convalescents, or even patients, suffer in a proportion very little greater, if at all greater, than those having no such intercourse—compared of course with the very many cases that are wont to occur in a widely spread epidemic.

Yet, though the general proportion may not be much affected, still we are ready to admit that a case does now and then occur, where disease is shortly observed after the admittance of a sick person in a house or locality, and where the effect is so marked, so immediate and so general among those exposed, that we are compelled to admit that there is room for thinking, that the patient is somehow or other, in some degree at least, the occasion of the catastrophe.

It is sometimes observed that servant girls, affected with typhus fever, are in that state sent to their homes, and that disease shortly affects their brothers and sisters, but before such cases can be held as proving the existence of atmospheric contagion, there should be a strong assurance that the agencies of a most unwholesome character, known to exist in such cases, are inert, and that they which have on other occasions, without assistance, produced of themselves the distemper observed, have been altogether impotent and inactive.

Their case produces the usual effect, demands the exertion of night watching, spoken of already, as favourable to the accession of disease, and their house or apartment, close and confined as it usually is in that rank of life, becomes the abode of many unwholesome influences, and among others, of an atmosphere, deprived in a great degree of its more essential part, and loaded, too, with foreign gases, and even perhaps with chemical compounds of a virulent character, the products of putrefaction. If disease spreads much among those thus exposed, it seems fair to attribute the occurrence to these agencies known to be present, and known to be favourable to the production of sickness, and not to atmospheric contagion, as is almost universally done.

The case of disease appearing in a house previously healthy, after receiving one just recovered of disease, which it is by the way consonant with our experience to say, is much more rare than the other, or that of persons actually ill,—is occasionally noticed, and the explanation, perhaps, is, that the clothes may retain impurities acquired during the course of disease, and may on this occasion shew their activity.

The question of the communication of atmospheric contagion from one place to another has almost universally, on occasions of pestilence, been much agitated, in respect to individual diseases, but seldom in a comprehensive way, embracing all diseases. We propose to inquire generally into the facts which are held to prove the principle of dissemination from one place to another—whether contagious atmosphere is transmitted from one country to another, from one town to another, and from hamlet to hamlet.

In the many works written by medical men on occasions of great epidemic disease, descriptive of the character of the prevalent distemper, there almost universally appear the most minute accounts of the route pursued by contagion, both fomitic and atmospheric, down to the noting of the very road, the very street or alley by which it reached a town—and of the manner in which it arrived, whether on the rags of a tattered beggar, or seated in a stage-coach.

The line of its progression is taken from the observation of disease, and from that alone. Wherever disease appears, there it is said that contagion has been carried or conveyed; and as a proof of that position, it is gravely maintained, that disease invariably breaks out where there are houses, and where communication is likely to be going on in some way or other. This most extraordinary fact proves what must certainly be thought not less extraordinary, that it appears in the abodes and habitations of men. But where else is disease, we would ask, to manifest itself, if among men at all, if not where alone they are to be found?—surely not among deserts uninhabitable, or on the frosty summit of an iceberg?

It is true that in the course of an epidemic, such as the cholera, one country suffers before another; but there is no alternative to such a course if they are not to be simultaneously affected. And it signifies nothing that communication subsists between them. One part of a country, too, is ravaged first, then another, and so on—one town then another—one part of a town, and after it another part.

But it is evident, that if disease is to begin at all, it must begin somewhere, and if all parts are not to be seized on the same instant, that one will have precedence of another, and so on. Springing and propagating, from whatever causes, that character must hold, and surely it is wrong to hold a feature common to the effects of many causes as decisive evidence of the operation of one, and of one only.

The harvests of Europe begin in one country, sooner than in another. In many, harvest is earlier than in England, but it is never surmised that when that process begins in the latter country, that it is through the mediation of some such influence as contagion. It begins in England, too, it might be shewn, in places having communication with foreign countries. Nay, it might also be proven that the parts in which it in general commences are at the coast, where it is well known ships are wont to appear.

Were such an insane supposition made, the most obvious facts would necessarily be laid aside; but such gross blindness would not, we are satisfied, be much greater, than when the process of diseased action, marked out in an epidemic, is attributed to contagious atmosphere alone.

In the case of the harvest, it would argue a forgetfulness of the object held in view when the seed was sown,—in that of disease, an ignorance of the effects to be expected from the sowing of the seeds of pestilence (the exposure to the common epidemic influences alluded to above), in the first, an insensibility to the influence of climate, intensity of sun’s rays, the quality of the soil, &c.:—And in the other, a blindness to the operation of circumstances not less potent, such as the time of application of the causes, the condition of the body, and the presence or absence of moral adjuvants.

It has universally held with all epidemic sickness, that parts of a country have been attacked in succession—that one town is visited after another, and one part of a town before another, whether the prevailing distemper have or have not been said to depend on contagion.

There is nothing extraordinary in the fact that all persons who are to suffer, do not become affected on one and the same day. Far from proving that any thing of the nature of contagion has been in operation, it only proves what may so readily be admitted, or at once readily understood, that all and sundry the inhabitants of a vast tract of country, inhabiting parts having different climates more or less mild, having different situations, some on the banks of rivers, some along the coast, some inland, some on boggy and some on dry soil; having different occupations, different houses, wearing different dresses, having different habits, different pursuits, different diet, different recreations, and perhaps having constitutions differing in aptitude to be acted upon, may not be all ready for the manifestation of disease on one and the same day, but may attain to that point at times corresponding with the operation of so many different circumstances.

In vegetation, which on the whole is much more simple than living animal organization, there is a gradation in the time at which its various individuals become ripe. The same grain is ripe in some districts weeks before it is ready in others, and even in the same farm, though the seed had been sown on the same day. Thus, by observing that the gradual development of disease over a country is the result of the varying activity and time of action of the epidemic influences, and perhaps of some condition of the body, varying in forwardness—it becomes unnecessary to have recourse to atmospheric contagion. It is unnecessary to repeat here what has been said relative to the operation of unwholesome agencies to account for the wide range of disease—over a country.

It is often said, as decisive proof of disease spreading by contagion, that a beggar, or some poor person left a town affected with disease, and entered another hitherto healthy—and that afterwards disease manifested itself there also.

In the first place, would not sickness have occurred notwithstanding? Its supporters say, not likely, when the effect followed, or immediately on the communication; but we reply, that communication took place before without any such immediate result, and that in all probability it had been going on freely all along, whatever regulation and hinderances might have been adopted.

It seems madness to think of stopping all communication with towns, in a free country such as this, where human intercourse is going on without interruption throughout the entire empire, or, indeed, anywhere at all, tolerably inhabited, or where commerce subsists.

It is in vain to endeavour to shew that opportunities for the transmission of contagious atmosphere have not occurred. The case involves an impossibility, for do not a thousand means of communication suggest themselves to the mind of the reader? The atmosphere itself, currents, winds, water, streams, &c.,—animals,—such as rats, mice, winged insects, &c. &c., which cannot be prevented from operating. We, therefore, leave this case, perhaps to the efforts of the advocates of quarantine regulations, who possibly may arrive at a happier result, and we proceed to the opposite case, where disease fails to spread, where communication does take place.

The advocates of contagion prove, where a disease appears in a town, that communication has taken place. That statement, as the reverse, can never be proven, is easily affirmed; and its insignificance corresponds with the facility with which it can be proven. Of course, it is obvious, that such a fact proves very little, either in reference to contagion or anything else.

We are prepared to prove, that communication has subsisted on many different occasions, without any unusual amount of sickness taking place. We know of many instances where disease has been prevailing in a town or village, which has failed to manifest itself in another at a short distance, although daily unrestrained communication was held.

At the end of the year 1835, and the beginning of the year 1836 the scarlet fever prevailed in Edinburgh to a great extent; and although great traffic was constantly going on between that town and Tranent, by means of foot-passengers, numerous carts and coaches, passing to and fro, daily, still that distemper failed to make its appearance in the latter town till the 20th of January, the day on which the first case was noticed.

That case did not occur at the point where the greatest thoroughfare subsists, but at one, the most remote from it.

Typhus fever has been prevailing, to a great extent, in Edinburgh, for many weeks past, but that disease has failed to make its appearance in Tranent (ten miles distant), although the road is constantly crowded with carriages, with vast numbers of carts conveying coals from that village to the capital, and with passengers both on horse and foot. It has not made its appearance, although several of the inhabitants of Tranent have lately lost relatives who have died of that disease, both in Edinburgh and Leith; and although a woman just recovered from that distemper, and come from the Royal Infirmary, has taken up her abode in this village.

Small-pox appeared about six weeks ago, simultaneously in two very filthy localities in Tranent, and it has been confined to them, although the most free communication has subsisted with other parts of the village, and it has failed to spread to the hamlets and farm-steadings around, notwithstanding the relatives of some of those labouring under that disease have travelled through the country, seeking charity.

We propose to close this part of the work. Much has been said in order to prove the position, that the doctrine of atmospheric contagion gains no support from the actual character of disease, no countenance from the ungarbled history of its career.

Arguments in favour of our views might have been drawn from the fact, that diseases said to be propagated by contagion, do not manifest themselves in all parts of the globe to which the poison would be likely to be taken, as they undoubtedly would do, were they dependent on the operation of one single object, such as contagious matter; and also from the consideration that those diseases, with whose causes we are intimately acquainted, by reason of their immediate operation, or of their being otherwise obvious, such as inflammation and wounds, are never said to be dependent on such an agency; but it is feared in the endeavour to be explicit, we have already been tiresome.

The question of air holding in solution, an animal contagious matter, eliminated in the body of a sick person, and capable of producing the same disease, when inhaled by another, has hitherto occupied our attention.

It is now our design to treat of vitiated air, that is, an atmosphere deprived of part of its more essential principle, viz. oxygen gas, or tainted with the admixture of effluvia or gaseous products, from putrefying animal bodies, both living and dead, and from corrupting vegetable matter.

It is one of the most common, and most widely spread causes, of the most virulent and widely prevalent diseases, to which humanity is subject.

The importance of the atmosphere to the animal economy, is so very great, and its derangements so very hurtful to health, that it appears that a few observations respecting it may be useful to some non-professional readers. It may enable them to understand better the observations that are to follow on its vitiation.

The atmosphere is a fluid of an elastic nature, encompassing the globe, occupying the space comprehended from its surface, to the distance of twenty or thirty miles therefrom. It possesses weight, and it is by this property that water rises in pumps, and that mercury is sustained in the barometer. It is in constant motion, going, as it does, with the globe itself, revolving on its axis, and rushing, in counter streams, from the tropics to the poles, and from the poles to the tropics.

That portion nearest the sun becomes rarefied and lightened with the heat which it acquires:—it then rushes, by virtue of its comparative lightness, to the poles, and that in temperate regions presses forward to occupy its place.

By means of this motion, the temperature of the earth is kept pretty uniform, and it is corrected of any impure taint it may acquire.

The atmosphere is composed of two gases, oxygen and nitrogen, a small quantity of watery vapour, and a fraction of carbonic acid gas, or fixed air.

Oxygen is the agent on which its more active properties depend. The other component, viz. nitrogen, serving to dilute it.

They are united in the proportion of about seventy-seven of nitrogen by volume, and twenty-one of oxygen, the rest being made up of watery vapour, and carbonic acid gas.

The atmosphere supports combustion,—oxygen gas being the essential agent. During combustion, it is consumed, and at the end of the process, it will be found wanting,—the other gas being undiminished.

This may be seen, at least the diminution in the volume of air, by burning a candle in a large wide mouthed bottle, inverted over coloured water. As it continues to burn, the water ascends in the bottle, and occupies the place of the oxygen consumed.

Atmospheric air supports respiration, a process essential to the continuance of life. Oxygen gas here, too, is the agent on which it depends. Air, which has been once respired, is found to be deprived of part of its oxygen, from ten to twelve per cent.

Air, deprived of oxygen, or even deprived of a small portion of it, is unfit for respiration. A mouse, put into a vessel containing air, which has been robbed of that fluid, dies immediately. Put into one containing pure air, it breathes well at first, but, as the oxygen gets less, its breathing becomes laboured, it is convulsed, and shortly dies.

The air is concerned, besides, in a thousand operations, constantly going on at the surface of the earth. It gives up a portion of its component parts in an immense number, and in a considerable proportion receives bodies foreign to its constitution.

By one set of operations, it is deprived of its oxygen, and becomes vitiated by the admixture of deleterious principles. By others, again, its oxygen is restored, and the impurities removed; so that between two opposite forces, it is in general kept in a wholesome condition.

An immense number of bodies on the surface of the earth, are constantly attracting to themselves the oxygen of the air; some become what is called oxydized, as the metals, the dull incrustation which is found upon them after long exposure to the air, being an oxide, or a combination of the metal, and the oxygen of the air. Some bodies become acids, as the various vegetable juices which form their respective acids, by combination with the oxygen of the atmosphere.

During fermentation, the oxygen is absorbed, and carbonic acid is evolved. During putrefaction, oxygen is taken up also. There are many operations, too, connected with the arts, in which that fluid is abstracted from the air. The very soil is constantly acting on the atmosphere, and is, indeed, one vast and extended laboratory, where chemical processes, on a large scale, are going on without interruption. The putrefaction of the animal and vegetable materials, used as manure, is much promoted by free exposure to the air; hence one of the advantages of ploughing the land so universally adopted. The very nature of the soil is greatly altered by that process, and much of that change depends not only on the chemical processes just spoken of, but upon the action of the air itself, on the essential particles of the clod. From the surface of newly turned up soil, it is understood by intelligent agriculturists, that much gaseous or elastic vapour is evolved; and we have heard it observed by intelligent ploughmen, that one of the most delightful things is the air which arises from newly ploughed fields in the morning. It is said that it imparts an invigorating, and wholesome sensation throughout the body, and from thence to the mind.

All those processes we referred to, abstract from the atmosphere its most essential part, the oxygen gas. Did that process of abstraction go on without its being counterbalanced by others, imparting that principle to supply the place of that abstracted, then the atmosphere in the course of time would become unfit to support combustion or flame,—unfit to support animal respiration; and the consequence would be, that the surface of the earth would soon be uninhabitable, would soon be a lifeless desert. Such would be the inevitable consequence.

But a wise and a good Creator has prevented the occurrence of that catastrophe. He has so ordered it, that one department of nature shall correct the bad tendencies of the other;—he has placed a weight at the opposite end of the balance, to counterpoise and balance the glorious work of his hand. Animal life is met by vegetable life: their results are made to neutralize those of each other, and with a wisdom truly the Father’s, found in his works alone, he has made the apparently hurtful consequence of animal life, the very means for the maintenance of the life of vegetation. The results of the function of respiration so necessary to animals, are highly useful to vegetables. Those products that are hurtful are absorbed by the leaves of plants, which are analogous to our lungs or breathing apparatus, and the oxygen consumed by animals is replaced by the evolution of a large quantity of that principle.

During sunshine, plants, especially in water, give out a large quantity of that principle, as may be seen by putting grass leaves into a jar filled with water, and exposing them to sunshine. Bubbles of air soon appear, and collect at the top of the jar; they are oxygen gas.

The evolution of oxygen gas in sunshine, is the chief means with which we are acquainted, by which the chemical equipoise of the atmosphere is maintained, against the operations constantly going on, to which we alluded.

These observations relate to the chemical composition of the air, considered as one great whole.

There are many situations in which it becomes not only deprived of its oxygen in part, but becomes vitiated by admixture with foreign bodies or vapours, most detrimental to health, in short, most pestiferous. But, before pointing out the manner in which it becomes so tainted, and its unwholesome consequences, we would here point out the use of the atmosphere. By the act of respiration, air is carried into the lungs; it acts upon the blood brought there in large quantities, and spread out in innumerable vessels, forming a sort of network. The blood, upon its arrival at the lungs, is dark, grumous, and unfit for the maintenance of life, and the nutrition of the body; but, under the action of the air, it becomes florid or crimson, has changes wrought upon it, by which it is fitted to perform its various and important functions.

This chemical process gives a crimson and florid hue to the old blood of the system, and imparts a colour and other qualities to the fluid brought from the bowels, the result of digestion, which give it the character of blood. It gives to that fluid the last preparation before being converted into blood.

The heat of the body, which is above that of the surrounding atmosphere, is maintained by the chemical changes which occur between the mass of blood in the lungs, and the air to which it is there exposed. There is a constant generation of heat, which is diffused along with the blood throughout the whole system,—to supply the place of that which is ever being abstracted by surrounding bodies, among which exists a constant tendency to preserve an equilibrium of temperature.

When the atmosphere is vitiated, it is reasonable to suppose, that the changes in the blood passing through the lungs will not take place in their wonted integrity, and that, among other results, a diminution of the vital heat of the body may be experienced.

Vitiated air admits of division into different kinds:—

1st, Into air simply deprived more or less of its oxygen.

2d, Into air holding in solution, or having mingled with it, effluvia from animal bodies, living and dead.

3d, Into air holding in solution, or having mingled with it, noxious gases or effluvia arising from decomposing vegetable matter.

Vitiated air, of every kind, is unwholesome and favourable to the invasion of disease.

Vitiated air has been coexistent with many of the most appalling visitations of disease, which have befallen man since the creation of the world. It delights in the production of the most formidable distempers, such as are marked with extreme debility and proneness to the putrefactive character.

The plague, in its various visitations, from the time of its prevalence in Athens, as described by Thucydides and Lucretius, down to the period when it last raged in England, viz. in the year 1665, has been observed to be coincident, for the most part, with circumstances proving the existence of vitiated air: and at this day the most mortal diseases prevail, where foul air exists, whether that arises from this or that source.

The atmosphere becomes vitiated, when great numbers of men in health are crowded together in apartments too close and confined to admit of a sufficient supply of pure air for the perfect maintenance of respiration. In this case, the vitiation is effected by the abstraction of the oxygen of the atmosphere, the exhalation of carbonic acid gas, and the dissemination of effluvia which arise from the bodies of those who are confined.

The immediate effects of confinement to an atmosphere thus vitiated are, oppressed breathing, sense of great anxiety and suffering, fixedness of the eyes, and torpor, which gradually increases to insensibility; and the miserable sufferer dies bereft of sense and motion, from suffocation.

When the atmosphere is not so impure as to cause immediate death, disease of a putrid character, for the most part takes place. Typhus fever attacked those persons who survived the memorable struggle in the black hole of Calcutta.

A low form of fever used to commit great havoc in jails and other places of confinement, where prisoners were wont to be crowded together in great numbers, from the atmosphere being deprived of its more vital part, and being loaded with unwholesome emanations arising from the filthy persons, and clothes of those confined.

This disease is called “Jail Fever,” and manifests a peculiarly malignant character.

In hospitals crowded with wounded soldiers, but otherwise in health, where sufficient ventilation cannot be maintained, the same distemper makes its appearance, and is there denominated “Hospital Fever.”

In besieged towns and in camps, where the inmates are exposed to the offensive and unwholesome effluvia, commonly experienced in such situations, the same putrid disease prevails, and goes under the name of “Camp Fever.”

AIR VITIATED WITH EFFLUVIA FROM BODIES IN A STATE OF DISEASE.

Air vitiated with effluvia from bodies in a state of disease, and their excretions, has been variously denominated.

By some it has been styled “Contagious Air;” by some “Infectious Air;” and, when it is in connection with fever, “Febrile Miasm or Contagion.”

Vitiated air of this kind differs from that referred to above, in this particular, that it arises from bodies in a state of disease.

Both forms of vitiated air produce, or assist to produce, disease of the same character; but as the latter form not only goes to produce disease, but arises from disease also, it has been considered to be analogous to the contagious poisons, such as those of small-pox, cow-pox, and the like.

From the circumstance of this vitiated air arising from persons in disease, and assisting in the propagation of the same malady, it has all along been regarded as a specific contagious animal poison in an atmospheric menstruum; and thus has been created the perplexing and entangled web of confusion and vagueness that has been wove around the principles, viz. contagious poisons, and vitiated air arising from effluvia from persons in disease, and from their excretions.

From this circumstance, these principles, viz. specific contagious poisons, and vitiated air arising from persons in disease, have been erroneously classed together, and a supposed analogy has been created.

But these principles are widely different in their nature, and in the laws by which they are regulated.

The specific contagious poisons produce the same diseases as those with which the bodies, whence they arose, were affected, and them only; and their operation is marked by uniform effects, observing stated and unvarying periods. Vitiated air, of the kind under examination, though it arises from persons in a state of disease, and is sometimes known to operate in the production or propagation of the same distemper, does not always induce disease, does not induce that disease only, whence it sprung, but various others; and, in short, its effects are not uniform, and do not observe stated and unvarying periods.

The specific contagious poisons produce their peculiar diseases, as their proper and only effects, without the cooperation of other influences; but vitiated air, when the same disease extends, whence it arose, cannot be said to be causing its proper, only, and peculiar effects, as the same disease does not invariably follow its action. In general, the effluvia which proceed from a sick person, where they prove hurtful, cause the same distemper as that with which he is affected; for instance, the effluvia arising from a person affected with typhus fever, produce that disease again:—but that is not always the case, and an instance will be presently detailed, where the effluvia which proceeded from a body dead of one disease, produced another of a very different nature.

The reason that the presence of vitiated air is generally attended with the same disease as that with which the body is affected, whence it sprung, is, that there is existing at the time, a disposition to that particular malady: and the vitiated air only gives it form by acting as an ordinary exciting cause upon individuals prepared for its invasion.

It appears probable that vitiated air, unlike the palpable contagious poisons, assists in the production of that disease only which is prevailing, or to which there exists a disposition from the operation of other agencies; and it appears probable that vitiated air, whether it arises from persons affected with this or that disease, will, within certain limits, produce one disease as readily as another, the required particular disposition being present; for instance, that the effluvia from a small-pox patient will induce small-pox or typhus fever, according as there exists a disposition to the one disease or the other, and vice versa.

The effluvia arising from newly opened graves have been often productive of putrid fever.

The following case will shew that effluvia arising from the remains of a person who died of consumption of the lungs, and not of small-pox, produced that disease, viz. small-pox. When that case occurred, small-pox was prevailing, and doubtless, had there been existing at the time a disposition to putrid fever, that disease, and not small-pox, would have been induced by the effluvia which arose from the grave.

In September 1834, Peter Macawley, about twenty-eight years of age, gardener and grave-digger, was employed in the churchyard of Tranent. While busily digging a grave, he unexpectedly struck a coffin with his spade, and broke it open. The coffin contained the remains of an old woman, who had died of consumption of the lungs, and who had been interred about fourteen months.

There immediately issued from the coffin the most offensive effluvia, which threatened suffocation, and made him feel very unwell.

He proceeded home, and continued throughout the night very poorly, giddy, and uncomfortable. He rose next morning, and although no better, proceeded to the churchyard, gave some directions, and returned home, feeling giddy and unsteady. He was put to bed, and passed a very uncomfortable night.

Called in next morning to prescribe for him, I found him to be affected with severe pain of head, great heat and sweating of skin, and great quickness of pulse. He complained of thirst, could take no food, and was occasionally delirious. On the third day of his illness, pimples appeared over the whole surface of the body, which gradually becoming larger, assumed the form of small-pox. The pocks or pustules did not mature or fill with matter in the usual way, but continued throughout to be flat, and assumed a dark blue or inky colour.

His strength fast declined,—he became very low,—muttered incoherently to himself, and symptoms of a putrid character supervening, and the energies of the system fast failing, he died insensible about the twelfth day of his illness, of the worst form of immature, putrid, confluent small-pox I had ever witnessed.

He was a powerful, well-formed, and laborious man, was in good general health up to the moment of his being affected in the grave,—and it was not ascertained that he had been in a situation to receive infection from any other source.

Vitiated air arising from persons in a state of disease, is found in those situations only where the apartment is close and confined, where the person and clothes are allowed to remain in a state of impurity, where the secretions and excretions are left to ferment; and, in short, where no attention is paid to cleanliness, the removal of respired air, and the introduction of a fresh atmosphere. The production of vitiated air is thus only occasional, while, in the contagious diseases, the specific poisons are produced in every case of their respective diseases, and were they capable of being diffused in the atmosphere, there would be present as constantly an atmospheric contagion.

When vitiated air is produced, its removal can readily be accomplished, as daily experience, and the testimony of Dr Haygarth, given at the beginning of this work, amply prove.

AIR VITIATED WITH EFFLUVIA FROM DEAD ANIMAL MATTER.

There is still another source whence effluvia of a pestiferous nature arise. Dead animal matter, during putrefaction, exhales gases which taint the atmosphere, and render it unwholesome.

When these materials are exposed to heat and moisture, the decomposition is rapid, and the air becomes more obviously tainted than when that process is retarded by cold, breezy weather, and some other circumstances. When the decomposition takes place in the open air, and when that is kept in motion, the quantity of decomposing materials not being very great, the bad effects are not so serious.

When, however, buried along with a sufficient quantity of atmospheric air, to allow of the play of the chemical affinities, and kept there a considerable time, if they be exhumed previous to their total digestion or complete assimilation with surrounding objects, effluvia are exhaled, having the most intolerable stench, causing instant sickness, faintness, and giddiness, and eventually producing disease.

“Thus, we are told by Fourcroy, that in some of the burial-grounds of France, whose graves are dug up sooner than they ought to be, the effluvium from an abdomen, (belly), suddenly opened by the stroke of the mattock, strikes so forcibly upon the grave-digger, as to throw him into a state of asphyxy, if close at hand; and if at a little distance, to oppress him with vertigo, fainting, nausea, loss of appetite, and tremors for many hours: whilst numbers of those who live in the neighbourhood of such cemeteries labour under dejected spirits, sallow countenances, and febrile emaciation.”^[5]

Instances are likewise known where graves containing human bodies, long dead of plague, upon being opened, have emitted effluvia, which have produced typhus fever among the workmen.

It is probable that, in general, the effluvia arising from dead animal materials, undergoing decomposition in the ordinary way, are the common results of the putrefactive fermentation,—carbonic acid gas, hydrogen, nitrogen, &c.

These gases form various combinations; carbonic acid gas and hydrogen gas forming carburetted hydrogen, an inflammable gas, the same as is used for the purpose of illumination, and which cannot support respiration. Hydrogen unites with nitrogen, and forms ammonia, or spirit of hartshorn, which is volatile, and imparts a strong odour to the atmosphere, such as is experienced in stables and byres, producing sneezing and watering of the eyes.

Hydrogen, at its extrication, sometimes carries with it a portion of phosphorus, already contained in the decomposing body, and becomes phosphuretted hydrogen, a gas which ignites spontaneously in the atmosphere, the same that is sometimes observed in churchyards under the title of corpse-lights.

Hydrogen sometimes also unites with sulphur, and the combination is called sulphuretted hydrogen, a gas readily discovered by its offensive odour,—which it imparts to many very useful mineral waters.

These gases are discovered, not only in an atmosphere exposed to decomposing dead animal materials, but are also found in that atmosphere containing numbers of men in health, closely crowded together, and persons suffering putrid diseases, where no attention is paid to cleanliness and the removal of impurities.

A body affected with putrid disease is more liable to decomposition than one in health; and the secretions and excretions are more prone to putrefaction, and the emission of effluvia or gases.

Some facts are known, which shew that bodies, in some forms of low or malignant disease, both before and after death, possess a virulence, never found in bodies in health, or affected with disease of a non-malignant character. The worst consequences have followed wounds in the dissection of bodies recently dead of typhus fever; the introduction, under the skin, of the fluid contained in the petechiæ or black spots common in that disease, and even the washing of bandages and clothes employed in cases of mortification and the like.

In such diseases, the body becomes a very centre of contamination and virulence; its fluids become acrid and poisonous; and on the surface of the body, fluids are elaborated, which are productive of the most malignant and pestiferous effects. Whether these fluids, those virulent secretions, are ever diffused in the air, and impart to it their deadly properties, is a point of much interest, but one which cannot be entertained here.

It is not only from such sources as those already treated of, that effluvia or gases arise, to contaminate the atmosphere, and to spread disease among men and beasts. Effluvia likewise spring from the putrefaction of vegetables; and, in many instances, from circumstances favourable to their development and action, they so vitiate the atmosphere, that its respiration induces some of the most virulent diseases, and, where the effects are not so serious, a state of slow sickness and great suffering is often the lot of the sufferer, during the whole course of his miserable existence. The situations of these effluvia will shortly be pointed out, along with the respective diseases incident to them.

But let us for a moment consider the changes on which these effluvia depend. Putrefaction of vegetable matter is one of the many wise provisions which the Almighty has instituted for the accomplishment of his comprehensive plan of the creation.

The surface of the earth is covered with vegetation, to supply man with food, and likewise to support the various animals placed below him in the scale of creation, so necessary to his comfort and existence. They are consumed, and, by means of digestion, become component parts of animals; and when these, in their turn, die, they go down to the earth, whence they originally sprung.

Mixed there, with other matters composing the soil, the carcasses of animals afford nourishment to vegetation again, and once more they are found as the component principles of vegetable forms. Thus the animal is constantly supplying food to the vegetable world, which, in its turn, supplies food to the other again.

In life, we found them performing functions useful to each other, and mutually correcting their unwholesome effects; in death, they are no less useful: the one is converted into the other.

All animated creation is the scene of endless changes, and is the object of successive transformations. ’Tis one mighty circle, of a thousand parts, constantly revolving,—one part occupying now this, now that place,—and each taking the place of that next it, till at length it completes the entire circle; and even then the race is not yet run, the revolution must be performed again and again, to the very end of time.

The immediate agency by which these wonderful changes are effected, is putrefaction. We have alluded to it shortly, in connection with man in health, in disease, and in death.

We have now to speak of putrefaction in connection with dead vegetable matter, in marshy situations, &c., where it is the occasion of much disease.

There is no reason to believe that it was the design of the Almighty, that the process of putrefaction, which is so essential to the great plan of successive races of animals and vegetables, should be the active engine of pestilence, which it is in many situations.

That is not the necessary consequence of putrefaction; and when it does occur, it is rather the effect of accidental circumstances. Under ordinary circumstances, where putrefaction goes on, as among vegetables moderately moist, exposed to currents of air, and mixed up with the soil, as in the various processes of agriculture, no bad results are experienced.

But when vegetation is allowed to go on year after year, without being cropped, where, as it ripens, it withers and dies; and when it dies, is allowed to accumulate and putrefy, where there is much moisture, much solar heat, and little motion of the air, where, perhaps, other circumstances are operating, favourable to rapid decomposition, effluvia are wont to ascend and vitiate the atmosphere.

Such a vitiated atmosphere has acquired various appellations, according to the place in which it has been observed, and according to the effects or diseases it produces.

But, under whatever name it passes, its origin is the same, namely, decomposing vegetable matter on the surface of the earth, perhaps, in some situations, mixed more or less with dead animal matter.

It is decomposing vegetable matter which produces the yellow fever of the West Indies, the jungle fever of India, the deadly pestilential fever of the coast of Africa, the ague in this country and in many others, the cretinism of Switzerland, the pellagra of Milan, the unwholesome condition of humanity in many parts of Italy, and especially in the country surrounding Rome, or the Campagna of Rome, as it is called. The decomposition, however, takes place under circumstances somewhat different, and hence the difference in the results of its action.

These effects are attributed to the decomposition of vegetable matter; but there is room to think that, along with that, there is combined no very insignificant proportion of matter of an animal nature.

It may safely be inferred, that wherever there is vegetation, there animals are found also; and it is well known that vast numbers of many kinds of animals live wherever decomposition is taking place, especially if the situation is warm and sheltered. The carcasses of these animals will be added to the vegetable matter, and add to the common mass of corruption.

That matter in swamps, and in unwholesome situations, said to be purely vegetable, is then a compound of animal and vegetable origin; and these effluvia arise, not from vegetable decomposition only, but from both dead animal and vegetable substances in a state of putrefaction.

There is little known of the composition of these effluvia. We are most conversant with their situations, and their effects upon health. In different situations, they produce different diseases. But no known facts entitle us positively to say that their composition is different. It is a remarkable fact, but one well ascertained, that the atmosphere, in all parts of the world, in all climates, and in all situations, is much the same in its chemical composition. It manifests the same general physical characters in all situations, whether healthy or pestilential, and the nicest investigations have detected nothing in an atmosphere known to be pestilential, that is not found in the most wholesome.

However, there is much reason to think, that this circumstance is owing, not to the absence of hurtful gases, but to the comparative insignificance of their volume beside that of the atmosphere itself, so vast in its dimensions.

Medical men have been disposed to think that effluvia which cause one disease, say the yellow fever, are not the same as that which cause another, say the fever of the coast of Africa. The only reason offered is the difference of the diseases; but that is not enough to prove that the effluvia are different in their nature. Different effects, or effects so modified as to appear very different, are the results of the same cause on many occasions. The smoke of tobacco will make one person feel comfortable, another merry, another sick, another faint, and so on; but it would be unfair, from these differences in the effects, to pronounce that tobacco-smoke was in all these cases different in its own nature.

We are satisfied that the effluvia or gases arising from marshy or unwholesome soil, are the same, generally speaking, in all situations, whatever disease is produced; and that the difference in the results is to be attributed to the varying circumstances under which they act,—for instance, the constancy or inconstancy of their operation, their greater or less intensity, the greater or less degree of concomitant moisture and heat, the greater or less amount of motion of the air,—the sheltered situation of human habitations,—the condition of the body, its predispositions from native country and the like, and the individual being accustomed or unaccustomed to the action of effluvia.

Gases are known to arise from the marshy grounds mentioned, where animal and vegetable matter is putrefying, from the fact, that the neighbourhood of swamps is most unwholesome, the inhabitants and visitors almost uniformly suffering, because unwholesome effluvia are invariably known to emanate where animal and vegetable matter is thus corrupting, and because the gases themselves may be seen rising in bubbles out of putrid water, containing dead animal and vegetable matter in a state of corruption.

These bubbles contain gases the very same as are disengaged when animal and vegetable matter are putrefying among water. They are nearly the same as proceed from merely animal matter dead and putrefying, not incorporated with the soil, viz. carburetted hydrogen, or inflammable gas, carbonic acid gas, or fixed air, and sometimes a little phosphuretted and likewise sulphuretted hydrogen.

These gases are sometimes appreciable to the organ of smell. Carburetted hydrogen is very strong, and is perceptible in many situations where there is much corruption going on; for instance, at the meadow-ground between the Dairy, on the Portobello road, and Comely Green, near Edinburgh, where the stench is so strong as to prove most offensive to passengers on the road. The source is the corrupting animal and vegetable materials, in the foul water conducted from Edinburgh, and made to overflow the ground, for the purposes of irrigation.

In such situations, it is not uncommon to observe lights floating along during the night, and superstition has not failed to make them represent evil spirits. They are known by the name of “Will o’ Wisp” and “Jack o’ Lantern;” and have, on many occasions, proved objects of no slight dread to many ignorant persons. The lights are merely ignited carburetted hydrogen gas,—the same kind of gas as that used for lighting our shops and houses.

The gas is ignited, perhaps, by the rising to the surface of the putrid water, of a bubble of phosphuretted hydrogen, which, as was before observed, burns the moment it comes in contact with the atmosphere.

Other products of an aeriform kind may be evolved also, but we have no direct evidence of their existence,—but an atmosphere, loaded with vapours of the kind mentioned, is enough to account for the production of the observed disease, in all its varied forms, when there is conjoined with it other unwholesome agencies. In some countries, the pestilential air is present throughout the year, for instance, in the country around Rome, in the fens of Lincolnshire, where ague is seldom absent; in others it is periodical, chiefly confined to the hot and rainy seasons, as in India and in the West Indies, where fevers prevail to a great extent; and in others, again, it is observed only when the wind blows from a particular direction.

These effluvia are conveyed to a distance by currents, and produce their peculiar effects, more or less, upon almost all they encounter. The malaria at Rome is carried by the wind into the city, by the channels most open to its entrance; and those parts, it is said by medical men who reside there, that are most exposed to the wind blowing off the adjacent marshy grounds, are most unhealthy. It is for that reason that the suburbs are more unwholesome than the interior of that city, where the wind does not find ready access, on account of the obstacles offered to its course by the high buildings. The high houses and streets thus act as a barrier against the entrance of the pestilence, and it is even said that the narrowest streets there, are the most healthy, as they shut out the pestilential vapour.

An obstacle of the same kind is offered by hills which interrupt the course of winds carrying with them vapours from marshy grounds. In the West Indies, where the yellow fever commits such frightful ravages, many instances are known where a town or district retains its health, from the shelter which a hill affords against the visitation of a wind that has loaded itself with deadly miasms, while sweeping over a marsh or swamp. It is the practice of those residing in those countries, not only to remove from the swamps, but also from those points to which the wind blows after passing over them.

Inattention to that consideration has led to the loss of much human life, and to the fruitless expenditure of much money in the erection of houses, barracks, and the like, which, after completion, have been found to be totally uninhabitable, from the pestilential vapours carried to them by the winds. In illustration of the influence of winds, we submit the following interesting extract from Dr Good’s Study of Medicine. He has been speaking of effluvia from animal matter. “But the foul and stinking Harmattan,” (a pestilential wind) “when it rushes from the south-east upon the Guinea coast, loaded with vegetable exhalations alone, with which it impregnates itself while sweeping over the immense uninhabitable swamps and oozy mangrove thickets of the sultry regions of Benin, triumphs in a still more rapid and wasteful destruction; so much that Dr Lind informs us, that the mortality produced by this pestilential vapour in the year 1754 or 1755 was so general, that in several negro towns, the living were not sufficient to bury the dead; and that the gates of Cape Coast Castle were shut up for want of sentinels to perform duty. Blacks and whites falling promiscuously before this fatal scourge.”

So loaded is the air on some occasions with these pestilential vapours, that they attach themselves to whatever objects they meet, houses, the sides of hills, and woods, through which they pass along with the wind, and so completely has a wood stripped the currents of their baneful accompaniments, that they have been respired after with no injury whatever.

Trees are found to give great shelter and salubrity to towns in this way, acting as they do as so many sieves retaining impurities.

It is understood that the effluvia arising from putrefying vegetable matters ascend high in the atmosphere under the influence of the solar rays, and spread far and wide, and that at night during the cold they fall with the dew to the ground again, and impart to it and to those exposed to its action, much virulence. The ground is there known to be extremely unwholesome, and those who have been compelled by want, by sickness, while travelling, overtaking them, or by being benighted, to lie down with nothing but the soil for a couch, and with no shelter from the vapours and dew that falls at night, save the sky itself, have felt this pestilential influence: on the morrow they awake distressed, parched, and affected with headach, and the usual symptoms of malignant fever.

With the close of day or the setting of the sun, the pestilential vapour falls and envelopes the country and the habitations of men with a deadly mantle—and it is then unsafe to venture into the open air in many of the finest countries of the world.

The pestilential effects of exposure to these night dews and vapours have, on many occasions, been experienced by soldiers encamping in the open grounds, and our gallant countrymen on foreign service are wont to yield in fearful numbers to a foe, merciless and unsparing.

But it is not in swampy grounds only that these vapours arise, for there is reason to think that in those places where sickness is constant, and where no such dampness of ground is observed, that decomposition of animal and vegetable matter is going on some depth below the surface, and that the extricated gases issue through the soil. This is rendered almost certain, by the fact which has sometimes been observed, that the most dangerous and sickly season is, when the ground is parched and rent with heat, permitting the exhalations generated below to ascend into the atmosphere. Instances of this occurred among our soldiers in the Peninsular war—the season, marked with the greatest prevalence of disease, the common result of vitiated air, being that when the soil was most rent with heat.

In some parts of Italy, it is remarked by that eminent physician and philosopher, Dr James Johnstone, in his admirable volume, entitled the Diary of a Philosopher, which, by the way, is a work of rare virtue, in so much as it is replete, not only with accurate medical knowledge, but with reflections in literature and the fine arts such as prove an intimacy with polite learning not always found, that fever and that general unwholesome state of body, observed in districts infested with vitiated air, prevail where inquiry has discovered no appearance of unusual dampness and corruption of the soil. He thinks that streams of putrid water, containing animal and vegetable materials, that have sunk down from the surface, in some part of their course are making their way at a little depth, and that when the soil, parched with excessive heat and drought, becomes rent, as it commonly does, the emanations previously confined rush out by the channels now presented by these fissures, and deal their deadly effects around.

Such an explanation seems to me highly probable, and deserving of more inquiry. Connected with this subject, the following facts may be interesting, and assist in forming an estimate of the probability of the truth of that explanation.

In mines, as well as on the surface of the earth, changes are constantly going on; and as in the latter situation the animal, vegetable, and mineral components of the soil are decomposing, so the minerals in the former are giving out some of their component parts and abstracting oxygen, &c. in turn from the atmosphere.

In mines some of the fossils attract oxygen from the air, but the chief process by which the atmosphere becomes vitiated there, is by the evolution of gases from the minerals. In coal pits the principal gases emitted are carbonic acid gas, commonly known as fixed air, which will support neither animal life nor combustion, as proved by the disastrous results on men having been confined in it, and by the extinction of light when immersed therein, and carburetted hydrogen gas, known as fire-damp, which cannot support respiration, and which takes fire when brought in contact with a light. These gases are the results of chemical changes going on in the minerals, in the same way as the gases before alluded to attend the decomposition of animal and vegetable substances.

These gases arise not only from the minerals exposed to view at the various surfaces, as the roof, sides, and pavement of coal pits, but issue also from the unworked minerals in the interior, by fissures or cracks in the various strata, produced by the violence used in detaching the minerals.

These fissures extend in the course of the beds, or strata, and are often scarcely visible, but are sometimes so wide as to admit the finger. It is probable that they sometimes extend a considerable way into the solid minerals.

In general, from these fissures there is constantly issuing streams of gas, of a nature varying with the character of the minerals, but for the most part they are such as have been mentioned. In the mines of Great Britain, when the atmosphere above is much agitated, as by the prevalence of southerly winds, and more especially if the violence amounts to what is termed a storm, the gases pour out in prodigious quantities, making a rushing noise, and filling the pit and excavated parts. The pit then becomes so full as to interfere with the operations of the men, who are frequently, for their safety, obliged to retire. In this case the atmosphere is lightened, and the pressure it is constantly exerting on all bodies with which it comes in contact is diminished, and the consequence is, that the gases rush out, under the circumstances already mentioned. It is known, that, during the prevalence of stormy weather, the mercury in a barometer falls; it is for a like reason, the weight upon it being less. Not only the gases issue from their caverns when the air is thus lightened, but water contained in fissures in the floor or pavement of mines rises also, sometimes to the amount of an inch or two, and it is no uncommon thing to see the extrication of vapour from a little collection of water on the floor, such as takes place when water is boiling, a movement which it very much resembles.

These facts shew that it is not improbable that pestilential vapours, ordinarily passing under the soil, may be extricated when fissures are present. It may happen that effluvia may be prevented from issuing even when fissures exist in the soil, from an increase in the weight of the atmosphere, and in this way may be explained the occasional disappearance of pestilence with a change of weather, not unfrequently remarked in some tropical countries.

During the prevalence of strong north, north-east, and north-west winds, blowing with considerable violence the currents in mines are reversed—for, instead of gases issuing from the fissures and crannies, currents of atmospheric air pour into them. These currents may be felt with the hand, and the ear can detect the rushing sound; a flame applied to a fissure is immediately drawn in, shewing the direction of the current. These facts illustrate the influence which the state of the atmosphere has upon terrestrial vapours.

As has been already observed, the exhalations from the soil obtain different names from the effects they are wont to produce. When they produce intermittent fever or ague, they are termed marsh miasms. When they produce the various forms of malignant fever, such as the yellow, the bilious fever of India, and the coast of Africa, simply pestilential effluvia—and when they induce general bad health and degeneracy of the inhabitants of a country, they are styled malaria, an Italian expression signifying bad air.

As the subject appears one which may interest the general reader, it is proposed to add a few observations on the diseases which are caused by air vitiated with effluvia from the soil.